A group of eagle-eyed puzzlers, using digital tools, has uncovered a pattern of copying in the professional crossword-puzzle world that has led to accusations of plagiarism and false identity.

Since 1999, Timothy Parker, editor of one of the nation’s most widely syndicated crosswords, has edited more than 60 individual puzzles that copy elements from New York Times puzzles, often with pseudonyms for bylines, a new database has helped reveal. The puzzles in question repeated themes, answers, grids and clues from Times puzzles published years earlier. Hundreds more of the puzzles edited by Parker are nearly verbatim copies of previous puzzles that Parker also edited. Most of those have been republished under fake author names.